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Crazy fuel problem

I have a new customer that has been having an issue with his car. The car has an intake wally 255hp, and an inline 255hp. It's running stock hard lines. The feedline is -6 from the fuel pump to the rail, and the feed is -6 to the AFPR and -4 from the AFPR to the stock hard line. The car was on the dyno for about an hour today, and was making pretty damn good power till it started loosing pressure. We pulled it off the dyno to diagnose the issue. Both pumps are turning on, but the intank pump is super hot. Not only is pump hot, the fuel in the tank was probably around 100*. Keep in mind this is E85!! I am thinking it's the pumps getting super hot due to them having to fight to get all that fuel back to the tank through the stock return line, which is pretty damn small.

Any thoughts on this predicament?
 

TylerAdamson

Well-known member
Joined
Dec 26, 2007
Messages
1,034
Location
Iowa City, Iowa
I'm a bit confused. You say he's running stock hard lines, but then you say he's got -6 feed and then -6 to the FPR and -4 to the return. Either way the stock return line is sufficient enough for 500+hp. I'd suggest getting rid of the -4 line though and replacing it with rubber 5/16'' fuel line.

As for your problem, have you checked the regulator? I've seen regulators fail from time to time so its not out of the question.
 

Regulator was holding just fine till about 1 hour into the session. I am starting to think it's a chinese walbro. They have the same symptoms and it was changed about 3 weeks ago, about the time it started having these issues.
 
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